First, the kraft paper issue: cost is a factor in adding the "sheen"-like coating to the final product. Last roll from LJ I got was "reverse wound", meaning the shiny side was on the "bottom" as you unrolled it, So check your roll to see if yours is reverse wound.
Now I'm curious: with all the moaning over pricing and competition, do you guys using Lineco or Tyvek increase your costs to cover the additional pricing of these covers?
And with all respect to Hugh: if you're framing a kid's piece with a lifespan of five years, this really isn't the same as grandma's needleart. so maybe you need two rolls of backing paper? One inexpensive for the kiddy art and one for the higher-end stuff???